A high efficiency class A amplifier accompanied by class D switching amplifier

A high power class A amplifier has excellent fidelity but dissipates too much power. A class D amplifier has high efficiency but shows poor fidelity. This paper proposes a combination of a high fidelity class A power amplifier with class D power amplifier as variable power supply. This amplifier named as class I has the merits of both class A amplifier and class D. The efficiency is seventy-seven percent at full power rating. The distortion of the proposed amplifier is about the same as that of class A amplifier. The measured 3 dB bandwidth is from 10 Hz to 100 kHz.